The invention relates to a hybrid drive for vehicles.
An article was published in the Engineering and Economy section of VDI Nachrichten, issue dated 21 Jan. 2005, No. 3, that explains mixed drives (hybrid drives) comprised of internal combustion engines and electric engines for automobiles. A mixed drive is described therein, that is made from a gasoline engine and an electric engine. In normal operation, the engine power is branched. A portion of the power flows directly via a planetary gear and the other portion of the power flows via a generator and the electric engine, a rechargeable battery being fed. Each power branch is oriented toward attaining the highest possible efficiency for the total system.
A report by the Chemnitz University of Technology, that was published on the Internet, concerns a stepless vehicle transmission with electromechanical power branching (SEL), which has to do with the mixed drive described in the foregoing. It is considered a serious disadvantage of the previously addressed transmission, that the output torque can never be greater than the total of the torques from the ring gear and electric engine on the output side. In this design, the ring gear torque is always lower than the path torque or torque of the combustion engine, which is itself low, no more than 150 Nm. Even a light vehicle requires output torques of 600 Nm or more for high accelerations and high climbing ability. With the drive design addressed in the foregoing this requires a very large drive.
The suggested first principle is retained with the SEL design that is also described in the TU Chemnitz article, but the disadvantages are eliminated. In addition it is suggested that for building higher output torques, the ring gear torque of the shaft is transmitted to the output in a further planetary gear step with high transmission ratio. In this way, the two planet wheel steps then should effect a high transmission ratio, wherein it is possible to produce drive torques greater than 1000 Nm.
Even if it is possible to provide a positive refinement in terms of the output torque by such approach, it is still disadvantageous that a second planetary step must be used that makes the transmission more expensive.
The goal of the subject-matter of the invention is to further develop the prior art such that when using a single planetary gear, or a single planetary gear step, mechanically linked to a relatively small electric engine and also with significantly reduced shifting, it is still possible to factor in the maximum capacity in each of the speed ranges for the vehicle.